Cost-effective optical chirped duobinary transmitter using an electroabsorption modulated laser

We propose and demonstrate a cost-effective way to implement a 10-Gb/s chirped duobinary (CDB) transmitter using an electroabsorption modulated laser (EML) followed by a LiNbO₃ Mach-Zehnder modulator both driven with binary signals. Successful transmission is achieved over 285 km of dispersion-uncompensated standard single-mode fiber without significantly increasing the complexity and cost of the transmitter, compared to conventional duobinary transmitters. The demonstrated CDB signals exhibit a superior performance to conventional duobinary signals, in terms of back-to-back receiver sensitivity and transmission distance. We achieve consistent transmission performance with three EMLs obtained from two different vendors, each having different chirp and transmission characteristics. Therefore, we believe the use of EMLs greatly reduces the implementation issues of 10-Gb/s CDB transmission systems.